How do I restrict one random prefab to be used only once but placed randomly with a whole bunch of prefabs of arrays on top of other object? - arrays

Question

How do I restrict one random prefab to be used only once but placed randomly with a bunch of prefabs of arrays on top of other object?
using System.Collections.Generic;
using UnityEngine;
public class LevelRoomsScript : MonoBehaviour
{
[SerializeField]
private GameObject[] memberWoodArray = null;
[SerializeField]
private GameObject[] memberRoomPrefabArray = null;
void Start()
{
foreach (GameObject localWood in memberWoodArray)
{
int localNumRoomPrefab = memberRoomPrefabArray.Length;
int localRoomIndex = Random.Range(0, localNumRoomPrefab);
GameObject localRoomPrefab = memberRoomPrefabArray[localRoomIndex];
Instantiate(localRoomPrefab, localWood.transform.position, Quaternion.identity);
}
}
}

Answer 1

The way I understand your question is that you want to instantiate each element in memberRoomPrefabArray at most once.
You could create a temporary list that is a copy of memberRoomPrefabArray and remove each element that is instantiated before the next loop cycle.
void Start()
{
List<GameObject> temp = new List<GameObject>(memberRoomPrefabArray);
foreach (GameObject localWood in memberWoodArray)
{
int localRoomIndex = Random.Range(0, temp.Count);
Instantiate(temp[localRoomIndex], localWood.transform.position, Quaternion.identity);
temp.RemoveAt(localRoomIndex);
}
}
You might want to add some checks like if (temp.Count == 0) { break; } if it's possible for memberRoomPrefabArray to be shorter than memberWoodArray.
Edit: Changed Random.Range(0, temp.Count - 1) to Random.Range(0, temp.Count) since, apparently, it's only maximally inclusive with floats and not integers.

Answer 2

You rather want to "shuffle" the array once and then iterate the shuffled array e.g. using Linq OrderBy and using Random.value as order like
using System.Linq;
...
void Start()
{
if(memberRoomPrefabArray.Length < memberWoodArray.Length)
{
Debug.LogError($"Not enough prefabs available for {memberWoodArray.Length} unique spawns!", this);
return;
}
// as the method names suggest this will be a randomized array of the available prefabs
var shuffledPrefabs = memberRoomPrefabArray.OrderBy(m => Random.value).ToArray();
for (var i = 0; i < memberWoodArray.Length; i++)
{
// Since the array is already shuffled we can now go by consecutive order
Instantiate(suffledPrefabs[i], memberWoodArray[i].transform.position, Quaternion.identity);
}
}